Cyclone assembly for surface cleaning apparatus and a surface cleaning apparatus having same

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 15/137,814, filed on Apr. 25, 2016, which is still pending, the disclosure of which is incorporated herein by reference in its entirety.

FIELD

This disclosure relates generally to cyclone assemblies for surface cleaning apparatus, and more specifically to cyclone assemblies that have first and second cyclonic cleaning stages.

INTRODUCTION

Various types of surface cleaning apparatus are known, including upright surface cleaning apparatus, canister surface cleaning apparatus, stick surface cleaning apparatus, hand carriable surface cleaning apparatus, and central vacuum systems.

Surface cleaning apparatus that use one or more cyclonic cleaning stages to remove particulate matter (e.g. dust and dirt) from an airstream are known.

A second cyclonic cleaning stage, which may comprise a plurality of cyclones in parallel, may be provided downstream of a first cyclonic cleaning stage and upstream of the suction motor. The second cyclonic cleaning stage is typically provided to remove particulate matter from the airstream exiting the first cyclonic cleaning stage and was not removed from the airstream by the first cyclonic cleaning stage.

Typically, second stage cyclones are effective at removing additional particulate matter from the airstream. However, a pre-motor filter is often provided downstream of the first cyclonic cleaning stage and upstream of the suction motor to protect the suction motor by filtering out particulate matter from the airstream that was not removed from the airstream by either the first or second cyclonic cleaning stage. However, there may be one or more disadvantages associated with providing a pre-motor filter. For example, the pre-motor filter may become clogged with particulate matter, requiring a user to clean and/or replace the filter, a task a user may regard as undesirable.

SUMMARY

The following introduction is provided to introduce the reader to the more detailed discussion to follow. The introduction is not intended to limit or define any claimed or as yet unclaimed invention. One or more inventions may reside in any combination or sub-combination of the elements or process steps disclosed in any part of this document including its claims and figures.

In accordance with one aspect of this disclosure, a cyclone assembly that may be used as an air treatment member to remove particulate matter (e.g. dirt, dust) from an airflow includes a first cyclonic cleaning stage and a second cyclonic cleaning stage located downstream of the first cyclonic cleaning stage wherein the second cyclonic cleaning stage includes a greater number of cyclone chambers than the first cyclonic cleaning stage. The first and second cyclonic stages are configured to provide reduced back pressure caused by air flow through the cyclonic stages. To this end, the cyclone chambers of the second cyclonic cleaning stage may be taller than the cyclone stage(s) of the first cyclonic cleaning stage.

In order to reduce backpressure through such a cyclone assembly, it is preferred that the velocity of the airflow entering the first cyclonic cleaning stage is approximately equal to the velocity of the airflow entering the second cyclonic cleaning stage. While the airflow velocity through the first stage air inlet is preferably approximately equal to the airflow velocity through each of the second stage air inlets, the separation characteristics of the first and second cyclonic cleaning stages may nonetheless be different. For example, if a second stage cyclone chamber has a smaller radius than the first stage cyclone chamber, particles entrained in the airflow in the second stage cyclone will experience a greater centrifugal force than they experienced in the first stage cyclone, which may promote the dis-entrainment of smaller particles from the airflow in the second cyclonic cleaning stage.

In an effort to achieve relatively equal airflow velocities (e.g., ±25%, ±20%, ±15%, ±10%, ±5%, the total cross-sectional area of the air inlet(s) of the first cyclonic cleaning stage is preferably approximately equal to the total cross-sectional area of the second stage air inlets (i.e. the sum of the cross-sectional areas of each second stage cyclone chamber air inlet). If the first cyclonic cleaning stage comprises a single cyclone chamber, then the total cross-sectional area of the air inlet of the first cyclonic cleaning stage is preferably approximately equal to the total cross-sectional area of the second stage air inlets.

However, due to boundary layer effects at the perimeter, the effective cross-sectional area of an air inlet may be smaller than the physical dimensions of the inlet. For example, for a rectangular air inlet of height H, width W, and assuming a constant boundary layer thickness L_B, the effective cross sectional area for the inlet may be estimated as: &lt;br /&gt;Area_Effective=(<i>H</i>−(2<i>×L</i>_B))×(<i>W</i>−(2<i>×L</i>_B))=<i>HW−</i>2(<i>HL</i>_B<i>+WL</i>_B−2<i>L</i>_B²).

If the second cyclonic cleaning stage has a larger number of second stage cyclones than the first cyclonic cleaning stage, and therefore a larger number of air inlets, and the sum of the cross sectional areas of the first stage air inlets is equal to the sum of the cross sectional areas of the second stage air inlets, then the sum of the effective cross sectional areas of the first stage air inlets may be less than the sum of the effective cross sectional areas of the second stage air inlets. The reason for this is that the total effective cross-sectional area of the second stage air inlets may be reduced by a greater amount than that of the first stage air inlet(s) as the boundary layer thickness at the perimeter of an inlet is typically not dependent on the area of the inlet. To adjust for this imbalance, the total cross-sectional area of the second stage air inlets, and optionally the cross-sectional area of each second stage air inlet, may be increased by about 5 to 30%, preferably about 10 to 20%, and more preferably by about 15% over what would be required to provide an approximately equal total physical inlet area for the second stage.

Also, it may be assumed that, generally, during each revolution within a cyclone chamber, an air stream moves in the longitudinal direction towards an end of the cyclone chamber by about the height of the cyclone chamber air inlet. For example, in a cyclone chamber that has a longitudinal height that is five times greater than the longitudinal height of its air inlet, the air may be expected to rotate about five times as it travels from the end of the cyclone chamber that has the air inlet to the opposite end of the cyclone chamber.

Accordingly, to provide first and second stage cyclones that have about the same number of turns within their respective cyclone chambers, each cyclone chamber preferably has a similar ratio of the longitudinal height of its air inlet to the longitudinal height of the cyclone chamber. Thus, where the longitudinal height of the air inlet for each second stage cyclone chamber is greater than the longitudinal height of the air inlet for the first stage cyclone chamber, the height of each second stage cyclone chamber is preferably greater than the height of each first stage cyclone chamber.

In accordance with this broad aspect, there is provided a cyclone assembly for a surface cleaning apparatus comprising: <ul id="ul0001" list-style="none"><li id="ul0001-0001" num="0000"><ul id="ul0002" list-style="none"><li id="ul0002-0001" num="0016">(a) a first cyclonic cleaning stage comprising at least one first stage cyclone having a first stage cyclone chamber, each first stage cyclone having a first stage longitudinal cyclone axis about which the air rotates in the first stage cyclone chamber, each first stage cyclone chamber having a height extending between a first stage cyclone chamber air inlet and a first stage cyclone dirt outlet; and</li><li id="ul0002-0002" num="0017">(b) a second cyclonic cleaning stage downstream from the first cyclonic cleaning stage and comprising a plurality of second stage cyclones in parallel, each of the plurality of second stage cyclones has a second stage cyclone chamber having a second stage longitudinal cyclone axis about which the air rotates in the second stage cyclone chamber, each second stage cyclone chamber having a height extending between a second stage cyclone chamber air inlet and a second stage cyclone dirt outlet,</li><li id="ul0002-0003" num="0018">wherein the second cyclonic cleaning stage has a larger number of second stage cyclones than the first cyclonic cleaning stage, and wherein the height of each second stage cyclone chamber is greater than the height of each first stage cyclone chamber.</li></ul></li></ul>

In some embodiments, the second stage cyclone dirt outlets may be provided in sidewalls of the second stage cyclones.

In some embodiments, the first and second stage longitudinal cyclone axes may be generally parallel.

In some embodiments, the first and second stage cyclones may be inverted.

In some embodiments, some or all of the second stage cyclone chamber air inlets may have a height in a direction of the second stage longitudinal cyclone axis that is greater than a height of each first stage cyclone chamber air inlet in a direction of the first stage longitudinal cyclone axis.

In some embodiments, the height of some or all of the second stage cyclone chamber air inlets may be 1.25 to 2.5 times greater than the height of each first stage cyclone chamber air inlet.

In some embodiments, the height of each second stage cyclone chamber may be greater than the height of each first stage cyclone chamber by at least the height of the first stage cyclone chamber air inlet. Optionally, in some embodiments, each of the second stage cyclone chamber air inlets may have a height in a direction of the second stage longitudinal cyclone axis that is 1.25 to 2.5 times greater than a height of each first stage cyclone chamber air inlet in a direction of the first stage longitudinal cyclone axis.

In some embodiments, each of the second stage cyclone chamber air inlets may have a width in a direction transverse to the second stage longitudinal cyclone axis according to the following formula:

<maths id="MATH-US-00001" num="00001"><math overflow="scroll"><mrow><mrow><msub><mi>W</mi><mn>2</mn></msub><mo>=</mo><mrow><mfrac><msub><mi>W</mi><mn>1</mn></msub><mi>N</mi></mfrac><mo>±</mo><mrow><mn>15</mn><mo>⁢</mo><mi>%</mi></mrow></mrow></mrow><mo>,</mo></mrow></math></maths>&lt;br /&gt; wherein W₂is the width of the second stage cyclone inlets in a direction transverse to the second stage longitudinal cyclone axis; W₁is the width of the first stage cyclone inlets in a direction transverse to the first stage longitudinal cyclone axis; and, N is the number of second stage cyclones. Optionally, in some embodiments, some or all of the second stage cyclone chamber air inlets may have a height in a direction of the second stage longitudinal cyclone axis that is greater than a height of the first stage cyclone chamber air inlet in a direction of the first stage longitudinal cyclone axis. Optionally, in some embodiments, the height of some or all the second stage cyclone chamber air inlets may be 1.25 to 2.5 times greater than the height of the first stage cyclone chamber air inlet.

In some embodiments, each of the first and second stage cyclone chamber air inlets may have a cross sectional area and a total of the cross sectional areas of the second stage cyclone chamber air inlets may be greater than a total of the cross sectional area of the first stage cyclone chamber air inlets.

In some embodiments, the total of the cross sectional areas of the second stage cyclone chamber air inlets may be 1.1-2, 1.1-1.5 or 1.1-1.3 times greater than the total of the cross sectional area of the first stage cyclone chamber air inlets.

In some embodiments, each of the first and second stage cyclone chamber air inlets has a cross sectional area and a total of the cross sectional areas of the second stage cyclone chamber air inlets may be greater than a total of the cross sectional area of the first stage cyclone chamber air inlets.

In some embodiments, each of the first and second stage cyclone chambers has a cyclone chamber air outlet and each cyclone chamber air outlet has a cross sectional area and a total of the cross sectional areas of the second stage cyclone chamber air outlets may be greater than a total of the cross sectional area of the first stage cyclone chamber air outlets.

In some embodiments, the total of the cross sectional areas of the second stage cyclone chamber air outlets may be 1.1-2, 1.1-1.5 or 1.1-1.3 times greater than the total of the cross sectional area of the first stage cyclone chamber air outlets.

In some embodiments, the height of each first stage cyclone chamber may be selected such that air rotates 2-4 times in each first stage cyclone chamber and the height of each second stage cyclone chamber may be selected such that air rotates 2-4 times in each second stage cyclone chamber.

In some embodiments, the height of each first and second stage cyclone chamber may be selected such that air rotates about 3 times in each cyclone chamber.

In accordance with another aspect of this disclosure, at least a portion of, and preferably most or substantially all of a second stage dirt collection region may be positioned longitudinally above and overlying the first stage cyclone chamber. Providing the second stage dirt collection region in such a location may facilitate a more compact design of a two stage cyclone assembly.

In accordance with this broad aspect, there is provided a cyclone assembly for a surface cleaning apparatus comprising: <ul id="ul0003" list-style="none"><li id="ul0003-0001" num="0000"><ul id="ul0004" list-style="none"><li id="ul0004-0001" num="0036">(a) a first cyclonic cleaning stage comprising at least one first stage inverted cyclone having a first stage cyclone chamber and an upper end;</li><li id="ul0004-0002" num="0037">(b) a second cyclonic cleaning stage downstream from the first cyclonic cleaning stage and comprising a plurality of inverted second stage cyclones in parallel, each of the plurality of second stage cyclones has a second stage cyclone chamber,</li><li id="ul0004-0003" num="0038">wherein the second cyclonic cleaning stage comprises a second stage dirt collection region and at least a portion of the second stage dirt collection region is positioned longitudinally above the first stage cyclone chamber and overlying the first stage cyclone chamber.</li></ul></li></ul>

In some embodiments, the at least a portion of the second stage dirt collection region may be positioned on the upper end.

In some embodiments, the second stage dirt collection region may be external to the second stage cyclones.

In some embodiments, the second stage dirt collection region may comprise a plurality of second stage dirt collection chambers.

In some embodiments, each second stage cyclone chamber has a second stage cyclone dirt outlet, each of which may be provided in a sidewall of one of the second stage cyclones.

In some embodiments, the first cyclonic cleaning stage has a first stage dirt collection region that may be external to the at least one first stage inverted cyclone and each first stage cyclone chamber has a first stage cyclone dirt outlet which may be provided in a sidewall of the at least one first stage inverted cyclone.

In some embodiments, the cyclone assembly may further comprise an openable lid which closes an upper end of the second stage cyclones and the second stage dirt collection region wherein when the openable lid is in an open position, the upper end of the second stage cyclones and the second stage dirt collection region may be opened.

In some embodiments, the first cyclonic cleaning stage has a first stage dirt collection region that may be external to the at least one first stage inverted cyclone and the cyclone bin assembly has an upper end comprising the second stage dirt collection region and the upper end may be moveably to an open position in which the at least one first stage inverted cyclone and the first stage dirt collection region are open.

In some embodiments, when the upper end is in the open position the second stage dirt collection region may be closed.

In some embodiments, when the upper end is in the open position the second stage cyclones may also be opened.

In some embodiments, the cyclone assembly further comprises an openable lid which may close an upper end of the second stage dirt collection region wherein when the openable lid is in an open position, the upper end of the second stage dirt collection region may be opened and the openable lid may be openable when the upper end is in the open position.

In some embodiments, when the upper end comprises an upper openable lid which closes an upper end of the second stage dirt collection region and a lower wall, the lower wall may comprise an upper end wall of the at least one first stage inverted cyclone.

In accordance with another aspect of this disclosure, an upstream pre-motor filter chamber or manifold may be positioned facing, e.g., below, the second cyclonic cleaning stage and each of the second stage cyclone air outlets may have an outlet extend to an opening in a wall of the chamber or manifold. An advantage of this design is that fewer conduit walls and/or ducting may be required to direct airflow from the second cyclonic cleaning stage towards the pre-motor filter, which may simplify the design and/or construction of the cyclone assembly and/or surface cleaning apparatus, and/or may reduce backpressure through the surface cleaning apparatus.

In accordance with this broad aspect, there is provided a cyclone assembly for a surface cleaning apparatus comprising: <ul id="ul0005" list-style="none"><li id="ul0005-0001" num="0000"><ul id="ul0006" list-style="none"><li id="ul0006-0001" num="0052">(a) a first cyclonic cleaning stage comprising at least one first stage cyclone, which may be an inverted cyclone, having a first stage cyclone chamber and a first stage cyclone air outlet;</li><li id="ul0006-0002" num="0053">(b) a second cyclonic cleaning stage downstream from the first cyclonic cleaning stage and comprising a plurality of second stage cyclones in parallel, each of the plurality of second stage cyclones may be an inverted cyclone and may each have a second stage cyclone chamber, each of the second stage cyclones having a second stage cyclone air outlet; and</li><li id="ul0006-0003" num="0054">(c) a pre-motor filter chamber, which may be positioned below the second cyclonic cleaning stage, wherein each of the second stage cyclone air outlets has an outlet end in a wall forming an upstream pre-motor filter chamber.</li></ul></li></ul>

In some embodiments, the second cyclonic cleaning stage may be removable from the pre-motor filter chamber.

In some embodiments, the second cyclonic cleaning may have an openable bottom wall wherein the second stage cyclones are opened when the openable bottom wall is in an open position.

In some embodiments, the first cyclonic cleaning stage may have a first stage dirt collection region that is external to the at least one first stage inverted cyclone and the first stage dirt collection region may be opened when the openable bottom wall is in an open position.

In some embodiments, the second cyclonic cleaning stage may comprise a second stage dirt collection region and the cyclone assembly may further comprise an openable lid which closes an upper end of the second stage dirt collection region wherein when the openable lid is in an open position, the upper end of the second stage dirt collection region may be opened.

In some embodiments, the cyclone assembly may further comprise a header downstream of the first stage cyclone air outlet and upstream of the second stage cyclones wherein the header is positioned between the first the first stage cyclone air outlet and the pre-motor filter chamber.

In some embodiments, the second cyclonic cleaning may have an openable bottom wall wherein the second stage cyclones and the header are opened when the openable bottom wall is in an open position.

In some embodiments, the first cyclonic cleaning stage may have a first stage dirt collection region that is external to the at least one first stage inverted cyclone and the first stage dirt collection region may be opened when the openable bottom wall is in an open position.

In accordance with another aspect of this disclosure, a release mechanism may be provided which is moveable to two open positions wherein, in a first open position, a first lock is moved to an unlocked position and in a second open position, a second lock is moved to an unlocked position. An advantage of this design is that the same actuator may be used to unlock an upper end of a cyclone assembly that houses a second stage dirt collection area and to open an upper lid that opens the second stage dirt collection area.

In accordance with another aspect of this disclosure, a cyclone assembly may have an openable lower end, and when the openable lower end is in an open position at least a portion of an airflow passage between a first cyclonic cleaning stage and a second cyclonic cleaning stage is opened. An advantage of this design is that opening the lower end may provide access to the airflow passage e.g. for cleaning, and/or such a configuration may simplify the design and/or construction of the cyclone assembly and/or surface cleaning apparatus.

In accordance with this broad aspect, there is provided a cyclone assembly for a surface cleaning apparatus comprising:

(a) an openable lower end;

(b) a first cyclonic cleaning stage comprising at least one first stage inverted cyclone having a first stage cyclone chamber and an upper end;

(c) a second cyclonic cleaning stage downstream from the first cyclonic cleaning stage and comprising a plurality of inverted second stage cyclones in parallel, each of the plurality of second stage cyclones having a second stage cyclone chamber; and,

(d) an air flow passage from the first cyclonic cleaning stage to the second cyclonic cleaning stage, <ul id="ul0007" list-style="none"><li id="ul0007-0001" num="0000"><ul id="ul0008" list-style="none"><li id="ul0008-0001" num="0069">wherein the lower end is moveable between a closed position and an open position in which at least a portion of the air flow passage is opened.</li></ul></li></ul>

In some embodiments, the second cyclonic cleaning stage may comprise at least one second stage dirt collection region that is exterior to the second stage cyclone chambers and the at least one second stage dirt collection region is opened when the lower end is moved to the open position.

In some embodiments, the lower end may comprise a single pivotally openable panel.

In some embodiments, the lower end may comprise at least one outlet port for the second cyclonic cleaning stage.

In some embodiments, the cyclone assembly may further comprise an upper end that is moveable between a closed position and an opening position in which the first and second cyclone chambers are opened.

In some embodiments, the cyclone assembly may further comprise a first stage dirt collection region exterior to the first stage cyclone chamber and the first stage dirt collection region is opened when the an upper end is moved to the open position.

In some embodiments, the second cyclonic cleaning stage may comprise at least one second stage dirt collection region that is exterior to the second stage cyclone chambers and the at least one second stage dirt collection region is opened when the upper end is moved to the open position.

In accordance with another aspect of this disclosure, a cyclone assembly may have an openable upper end and an openable lower end, and when the openable upper end is in an open position, the cyclone chambers of the first and second cyclonic cleaning stages are opened, and when the openable lower end is in an open position, a dirt collection region for the first cyclonic cleaning stage and at least one dirt collection region for the second cyclonic cleaning stage are opened. An advantage of this design is that opening the upper end may provide access to each cyclone chamber and optionally one or more dirt collection regions e.g. for cleaning, and opening the lower end may provide access to one or more dirt collection regions for the first and/or second cyclonic cleaning stages, and/or such a configuration may simplify the design and/or construction of the cyclone assembly and/or surface cleaning apparatus.

In accordance with this broad aspect, there is provided a cyclone assembly for a surface cleaning apparatus comprising:

(a) an openable upper end and an openable lower end;

(b) a first cyclonic cleaning stage comprising at least one first stage inverted cyclone having a first stage cyclone chamber, an upper end and a dirt outlet at the upper end in communication with a first stage dirt collection region exterior to the first stage cyclone chamber;

(c) a second cyclonic cleaning stage downstream from the first cyclonic cleaning stage and comprising a plurality of inverted second stage cyclones in parallel, each of the plurality of second stage cyclones having a second stage cyclone chamber, an upper end and a dirt outlet at the upper end wherein the dirt outlets of the second stage cyclone chambers are in communication with at least one second stage dirt collection region exterior to the second stage cyclone chambers;

wherein the upper end is moveable between a closed position and an opening position in which the first and second cyclone chambers are opened, and

wherein the lower end is moveable between a closed position and an open position in which the first stage dirt collection region and the at least one second stage dirt collection region are opened.

In some embodiments, the second stage may comprise a plurality of second stage dirt collection regions and the plurality of second stage dirt collection regions are opened when the lower end is opened.

In some embodiments, the at least one second stage dirt collection region may be opened when the upper end is opened.

In some embodiments, the second stage may comprise a plurality of second stage dirt collection regions and the plurality of second stage dirt collection regions are opened when the upper end is opened.

In some embodiments, the cyclone assembly may further comprise an air flow passage from the first cyclonic cleaning stage to the second cyclonic cleaning stage, wherein at least a portion of the air flow passage is opened when the lower end is opened.

In some embodiments, the lower end may comprise at least one outlet port for the second cyclonic cleaning stage.

In accordance with another aspect of this disclosure, a cyclone assembly may have an openable upper end and an openable lower end, and when the openable upper end is in an open position, the cyclone chambers for the first and second cyclonic cleaning stages are opened and optionally one or more dirt collection regions, and when the openable upper end is in a closed position it may abut an upper end of sidewalls of the first and second cyclonic cleaning stages. An advantage of this design is that opening the upper end may provide access to each cyclone chamber e.g. for cleaning, and/or such a configuration may simplify the design and/or construction of the cyclone assembly and/or surface cleaning apparatus.

In accordance with this broad aspect, there is provided a cyclone assembly for a surface cleaning apparatus comprising:

(a) an openable upper end and an openable lower end;

(b) a first cyclonic cleaning stage comprising at least one first stage inverted cyclone having an air inlet and an air outlet at a lower end of a first stage cyclone chamber and a first stage dirt outlet provided in an upper portion of a first stage cyclone sidewall of the first stage cyclone chamber, the first stage dirt outlet in communication with a first stage dirt collection region exterior to the first stage cyclone chamber wherein the upper end abuts an upper end of the first stage cyclone sidewall when the upper end is in a closed position;

(c) a second cyclonic cleaning stage downstream from the first cyclonic cleaning stage and comprising a plurality of inverted second stage cyclones in parallel, each of the plurality of second stage cyclones having a cyclone chamber having an air inlet and an air outlet at a lower end thereof and a second stage dirt outlet provided in an upper portion of a second stage cyclone sidewall of the second stage cyclone chamber, wherein the second stage dirt outlets are in communication with at least one second stage dirt collection region exterior to the second stage cyclone chambers wherein the upper end abuts an upper end of the second stage cyclone sidewalls when the upper end is in a closed position,

wherein, when the upper end is in an open position, the first and second stage cyclone chambers are opened.

In some embodiments, the second stage may comprise a plurality of second stage dirt collection regions and the plurality of second stage dirt collection regions are opened when the lower end is opened.

In some embodiments, the lower end may comprise at least one outlet port for the second cyclonic cleaning stage.

In some embodiments, the at least one second stage dirt collection region may be opened when upper end is opened.

In some embodiments, the second stage may comprise a plurality of second stage dirt collection regions and the plurality of second stage dirt collection regions are opened when upper end is opened.

In some embodiments, the cyclone assembly may further comprise an air flow passage from the first cyclonic cleaning stage to the second cyclonic cleaning stage, wherein at least a portion of the air flow passage is opened when the lower end is opened.

In some embodiments, the lower end may comprise at least one outlet port for the second cyclonic cleaning stage.

A pre-motor filter is typically provided downstream of the cyclonic cleaning stages and upstream of the suction motor, to prevent particulate matter that is not removed from the airstream by the cyclonic cleaning stages from being drawn into the suction motor. Otherwise, this unremoved particulate matter may cause damage to (or otherwise impair) the suction motor. While the use of a pre-motor filter may be effective at protecting the suction motor, there may be one or more disadvantages. For example, the pre-motor filter may become clogged with particulate matter, requiring a user to clean and/or replace the filter, a task a user may regard as undesirable.

In some embodiments disclosed herein, all or substantially all of the dirt entrained in the air exiting the first cyclonic cleaning stage may be removed from the airflow by the second cyclonic cleaning stage. This may, for example, obviate the need to provide a pre-motor filter in the surface cleaning apparatus.

It will be appreciated by a person skilled in the art that an apparatus or method disclosed herein may embody any one or more of the features contained herein and that the features may be used in any particular combination or sub-combination.

These and other aspects and features of various embodiments will be described in greater detail below.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

For a better understanding of the described embodiments and to show more clearly how they may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which:

<figref idref="DRAWINGS">FIG. 1</figref> is a perspective view of a surface cleaning apparatus comprising a cyclone assembly in accordance with one embodiment;

<figref idref="DRAWINGS">FIG. 2</figref> is a perspective view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 3</figref> is a top perspective view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 2</figref>;

<figref idref="DRAWINGS">FIG. 4</figref> is a top perspective view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 2</figref>, with an upper lid in an open position;

<figref idref="DRAWINGS">FIG. 5</figref> is a top perspective view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 2</figref>, with an upper end in an open position and the upper lid in a closed position;

<figref idref="DRAWINGS">FIG. 6</figref> is a perspective view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 5</figref>, with portions of the outer wall removed for clarity;

<figref idref="DRAWINGS">FIG. 7</figref> is a bottom perspective view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 2</figref>;

<figref idref="DRAWINGS">FIG. 8</figref> is a bottom perspective view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 2</figref>, with a bottom in an open position;

<figref idref="DRAWINGS">FIG. 9</figref> is a cross-section view of the surface cleaning apparatus of <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 10</figref> is an enlarged view of the lower portion of <figref idref="DRAWINGS">FIG. 9</figref>;

<figref idref="DRAWINGS">FIG. 11</figref> is a section view of the cyclone assembly and suction motor housing of the surface cleaning apparatus of <figref idref="DRAWINGS">FIG. 8</figref>, taken along line <b>11</b>-<b>11</b> shown in <figref idref="DRAWINGS">FIG. 1</figref>;

<figref idref="DRAWINGS">FIG. 12</figref> is a cross-section view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 2</figref>, taken along line <b>12</b>-<b>12</b> shown in <figref idref="DRAWINGS">FIG. 2</figref>;

<figref idref="DRAWINGS">FIG. 13</figref> is a section view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 2</figref>, taken along line <b>13</b>-<b>13</b> shown in <figref idref="DRAWINGS">FIG. 2</figref>;

<figref idref="DRAWINGS">FIG. 14</figref> is a cross-section view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 2</figref>, taken along line <b>14</b>-<b>14</b> shown in <figref idref="DRAWINGS">FIG. 3</figref>, with a portion of the lower wall of the first stage cyclone removed to reveal a plurality of second stage cyclone chamber air inlets;

<figref idref="DRAWINGS">FIG. 15</figref> is a top view of the bottom of the cyclone assembly of <figref idref="DRAWINGS">FIG. 2</figref>;

<figref idref="DRAWINGS">FIG. 16</figref> is a cross-section view of the surface cleaning apparatus of <figref idref="DRAWINGS">FIG. 1</figref>, taken along line <b>16</b>-<b>16</b> shown in <figref idref="DRAWINGS">FIG. 1</figref>, with a release mechanism in a neutral position;

<figref idref="DRAWINGS">FIG. 17</figref> is a top view of the enlarged portion of <figref idref="DRAWINGS">FIG. 16</figref>;

<figref idref="DRAWINGS">FIG. 18</figref> is a cross-section view of the surface cleaning apparatus of <figref idref="DRAWINGS">FIG. 1</figref>, taken along line <b>16</b>-<b>16</b> shown in <figref idref="DRAWINGS">FIG. 1</figref>, with the release mechanism in a first unlocked position;

<figref idref="DRAWINGS">FIG. 19</figref> is a cross-section view of the surface cleaning apparatus of <figref idref="DRAWINGS">FIG. 1</figref>, with the release mechanism in a first unlocked position;

<figref idref="DRAWINGS">FIG. 20</figref> is a cross-section view of the surface cleaning apparatus of <figref idref="DRAWINGS">FIG. 1</figref>, taken along line <b>20</b>-<b>20</b> shown in <figref idref="DRAWINGS">FIG. 1</figref>, with the release mechanism in a second unlocked position;

<figref idref="DRAWINGS">FIG. 21</figref> is a top view of the enlarged portion of <figref idref="DRAWINGS">FIG. 20</figref>, with the release mechanism in a neutral position;

<figref idref="DRAWINGS">FIG. 22</figref> is a cross-section view of the surface cleaning apparatus of <figref idref="DRAWINGS">FIG. 1</figref>, with the release mechanism in the second unlocked position;

<figref idref="DRAWINGS">FIG. 23</figref> is a perspective view of a cyclone assembly in accordance with another embodiment;

<figref idref="DRAWINGS">FIG. 24</figref> is a rear perspective view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 23</figref>;

<figref idref="DRAWINGS">FIG. 25</figref> is a perspective view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 23</figref>, with an upper end in an open position;

<figref idref="DRAWINGS">FIG. 26</figref> is a top view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 23</figref>, with an upper end in an open position;

<figref idref="DRAWINGS">FIG. 27</figref> is a bottom perspective view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 23</figref>;

<figref idref="DRAWINGS">FIG. 28</figref> is a bottom perspective view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 23</figref>, with a lower end in an open position; and,

<figref idref="DRAWINGS">FIG. 29</figref> is a bottom view of the cyclone assembly of <figref idref="DRAWINGS">FIG. 23</figref>, with a lower end in an open position.

The drawings included herewith are for illustrating various examples of articles, methods, and apparatuses of the teaching of the present specification and are not intended to limit the scope of what is taught in any way.

DESCRIPTION OF EXAMPLE EMBODIMENTS

Various apparatuses, methods and compositions are described below to provide an example of an embodiment of each claimed invention. No embodiment described below limits any claimed invention and any claimed invention may cover apparatuses and methods that differ from those described below. The claimed inventions are not limited to apparatuses, methods and compositions having all of the features of any one apparatus, method or composition described below or to features common to multiple or all of the apparatuses, methods or compositions described below. It is possible that an apparatus, method or composition described below is not an embodiment of any claimed invention. Any invention disclosed in an apparatus, method or composition described below that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicant(s), inventor(s) and/or owner(s) do not intend to abandon, disclaim, or dedicate to the public any such invention by its disclosure in this document.

Furthermore, it will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the example embodiments described herein. However, it will be understood by those of ordinary skill in the art that the example embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the example embodiments described herein. Also, the description is not to be considered as limiting the scope of the example embodiments described herein.

In the examples discussed herein, the surface cleaning apparatus with which the cyclone assembly is used is an upright vacuum cleaner. In alternative embodiments, the surface cleaning apparatus may be another suitable type of surface cleaning apparatus, such as a canister type vacuum cleaner, a hand vacuum cleaner, a stick vac, a wet-dry type vacuum cleaner, a carpet extractor, and the like.

General Description of a Surface Cleaning Apparatus

Referring to <figref idref="DRAWINGS">FIG. 1</figref>, a surface cleaning apparatus is shown generally as <b>10</b>. The surface cleaning apparatus includes a surface cleaning head <b>12</b> and an upper portion <b>14</b> that is movably and drivingly connected to the surface cleaning head <b>12</b>. The surface cleaning head <b>12</b> may be supported by any suitable support members, such as, for example wheels and/or rollers, to allow the surface cleaning head to be moved across a floor or other surface being cleaned. The support members (e.g., wheels) may be of any suitable configuration, and may be attached to any suitable part of the surface cleaning apparatus, including, for example, the surface cleaning head and/or the upper portion.

The surface cleaning apparatus <b>10</b> includes a dirty air inlet <b>16</b>, a clean air outlet <b>18</b> and an air flow path or passage extending therebetween (See <figref idref="DRAWINGS">FIGS. 9-11</figref>). In the illustrated example, the air flow path includes at least one flexible air flow conduit member (such as a hose <b>15</b> or other flexible conduit). Alternatively, the air flow path may be formed from rigid members. A cyclone assembly <b>100</b> and at least one suction motor are provided in the air flow path. Preferably, the cyclone assembly is provided upstream from a suction unit <b>20</b> that contains the suction motor(s), but alternatively may be provided downstream from the suction motor(s). In addition to the cyclone assembly, the surface cleaning apparatus may also include one or more pre-motor filters (preferably positioned in the air flow path between the cyclone assembly and the suction motor) and/or one or more post-motor filters (positioned in the air flow path between the suction motor and the clean air outlet).

General Description of a Cyclone Assembly

<figref idref="DRAWINGS">FIGS. 2-8 and 12-15</figref> illustrate an embodiment of a cyclone assembly, referred to generally as <b>100</b>. Cyclone assembly <b>100</b> may be used as an air treatment member to remove particulate matter (e.g. dirt, dust) from an air flow. Preferably, the cyclone assembly is removable from the surface cleaning apparatus. Providing a detachable cyclone assembly <b>100</b> may allow a user to carry the cyclone assembly <b>100</b> to a garbage can for emptying, without needing to carry or move the rest of the surface cleaning apparatus <b>10</b>. Preferably, the cyclone assembly is removable as a closed module, which may help prevent dirt and debris from spilling out of the cyclone assembly <b>100</b> during transport.

As shown in <figref idref="DRAWINGS">FIG. 2</figref>, the cyclone assembly <b>100</b> has a lower end <b>102</b>, an upper end <b>104</b>, and an outer sidewall <b>108</b>. Preferably, an assembly handle <b>106</b> is provided at the upper end <b>104</b>. The assembly handle <b>106</b> may facilitate carrying of the cyclone assembly when it is detached from the surface cleaning apparatus <b>10</b>.

Referring to <figref idref="DRAWINGS">FIGS. 4-8 and 12-15</figref>, cyclone assembly <b>100</b> includes a first cyclonic cleaning stage and a second cyclonic cleaning stage located downstream of the first cyclonic cleaning stage. The first cyclonic cleaning stage includes a first stage cyclone chamber <b>110</b> that extends along a cyclone axis <b>115</b> and includes a generally cylindrical sidewall <b>111</b> extending between a lower end wall <b>113</b> and an intermediate wall <b>140</b> (which is an upper end wall of the cyclone chamber <b>110</b>). In the illustrated embodiment, the first stage cyclone chamber <b>110</b> is arranged in a generally vertical, inverted cyclone orientation. Alternatively, the first stage cyclone chamber can be provided in another orientation, for example as a horizontal or inclined cyclone and may be of any cyclone construction. Alternately, or in addition, the first cyclonic cleaning stage may comprise a plurality of cyclone chambers.

In the illustrated embodiment, the first stage cyclone chamber <b>110</b> includes a first stage cyclone air inlet <b>112</b> and a first stage cyclone air outlet <b>114</b>. First stage cyclone chamber <b>110</b> also includes at least one dirt outlet <b>118</b>, through which dirt and debris that is separated from the air flow can exit the cyclone chamber <b>110</b>. While it is preferred that most or all of the dirt exit the first stage cyclone chamber via the dirt outlet <b>118</b>, some dirt may settle on the bottom end wall <b>113</b> of the cyclone chamber <b>110</b> and/or may be entrained in the air exiting the first stage cyclone chamber via the air outlet <b>114</b>.

In the illustrated example, the first stage cyclone dirt outlet <b>118</b> is in the form of a slot bounded by the cyclone side wall <b>111</b> and the upper cyclone end wall <b>140</b>, and is located toward the upper end of the cyclone chamber <b>110</b>. Alternatively, the dirt outlet may be of any other suitable configuration, and may be provided at another location in the cyclone chamber, including, for example as an annular gap between the sidewall and an end wall of the cyclone chamber or an arrestor plate or other suitable member.

Preferably, the first stage cyclone air inlet <b>112</b> is located toward one end of the cyclone chamber <b>110</b> (the lower end in the illustrated example) and may be positioned adjacent the corresponding cyclone chamber end wall <b>113</b>. Alternatively, the cyclone air inlet <b>112</b> may be provided at another location within the first stage cyclone chamber <b>110</b>. Preferably, the air inlet <b>112</b> is positioned so that air flowing through the inlet and into the first stage cyclone chamber is travelling generally tangentially relative to, and preferably adjacent, the sidewall <b>111</b> of the cyclone chamber <b>110</b>.

The cross-sectional shape of the air inlet <b>112</b> can be any suitable shape. In the illustrated example of <figref idref="DRAWINGS">FIG. 12</figref>, the air inlet has a cross-sectional shape that is generally rectangular (e.g., it has rounded corners and can be referred to as a rounded rectangle) having a height H_I_{<sub2>1 </sub2>}in the longitudinal direction (i.e. parallel to cyclone axis <b>115</b>) and a width W_I_{<sub2>1 </sub2>}in a transverse direction cyclone axis <b>115</b>. The cross-sectional area of the air inlet <b>112</b> can be referred to as the cross-sectional area or flow area of the first stage cyclone air inlet <b>112</b>. Alternatively, instead of being a rounded rectangle, the cross-sectional shape of the air inlet may be another shape, including, for example, round, oval, square and rectangular.

Referring to <figref idref="DRAWINGS">FIG. 12</figref>, the first stage cyclone chamber <b>110</b> has a height H_C_{<sub2>1 </sub2>}in the longitudinal direction (i.e. parallel to cyclone axis <b>115</b>). The height of the first stage cyclone chamber <b>110</b> is preferably selected such that air entering the cyclone chamber via inlet <b>112</b> is expected to rotate approximately 3 to 6 times, 3 to 5 times, 2 to 4 times or three-and-a-half times in the first stage cyclone chamber prior to exiting the cyclone chamber via outlet <b>114</b>.

In general, it may be assumed that the airflow against the cyclone chamber sidewall as it progresses around the cyclone chamber maintains a degree of cohesion, and that during each revolution within a cyclone chamber, an air stream moves in the longitudinal direction towards an end of the cyclone chamber by a distance approximately equal to the height of the cyclone chamber air inlet. For example, in a cyclone chamber that has a longitudinal height that is five times greater than the longitudinal height of its air inlet, the resulting cyclone may be expected to rotate about five times as it travels from the end of the cyclone chamber that has the air inlet to the opposite end of the cyclone chamber.

Thus, in order to promote the formation of a cyclone that is expected to rotate about three-and-a-half times in the first stage cyclone chamber <b>110</b>, the height H_C_{<sub2>1 </sub2>}of the first stage cyclone chamber <b>110</b> may be between 3 and 4 times, the height H_I_{<sub2>1 </sub2>}of the first stage cyclone air inlet <b>112</b>.

Air can exit the first stage cyclone chamber <b>110</b> via the first stage air outlet <b>114</b>. Preferably, the cyclone air outlet is positioned in one of the cyclone chamber end walls and, in the example illustrated, is positioned in the same end as the air inlet <b>112</b> and air inlet <b>112</b> may be positioned adjacent or at the end wall <b>113</b>. In the illustrated embodiment the air outlet <b>114</b> is generally circular in cross-sectional shape. Preferably, the cross-sectional or flow area of the first stage cyclone air outlet <b>114</b> is generally equal to the flow area of the first stage cyclone air inlet <b>112</b>. In the illustrated example, the cyclone air outlet <b>114</b> comprises a vortex finder <b>116</b>.

Air exiting the first stage air outlet <b>114</b> may be directed into a chamber or manifold <b>117</b>. From there, the air is directed into the second cyclonic cleaning stage. The second cyclonic cleaning stage includes a plurality of second stage cyclone chambers <b>120</b> arranged in parallel. In the illustrated embodiment, six second stage cyclone chambers are shown, referred to as <b>120</b><i>a</i>, <b>120</b><i>b</i>, <b>120</b><i>c</i>, <b>120</b><i>d</i>, <b>120</b><i>e</i>, and <b>120</b><i>f</i>, respectively.

In the illustrated embodiment, each second stage cyclone chamber <b>120</b> is arranged in a generally vertical, inverted cyclone orientation. Alternatively, the second stage cyclone chambers can be provided in another orientation, for example as horizontal or inclined cyclones and may be of any cyclone construction.

In the illustrated embodiment, each second stage cyclone chamber extends along a respective cyclone axis <b>125</b> (see e.g. <figref idref="DRAWINGS">FIGS. 5 and 13</figref>) and extends between a lower end wall or bottom <b>130</b> and an upper end wall <b>150</b>. In the illustrated embodiment, each second stage cyclone chamber is bounded by a lower sidewall <b>121</b> and an upper sidewall extension <b>141</b>.

In the illustrated embodiment, each second stage cyclone chamber <b>120</b> includes a second stage cyclone air inlet <b>122</b> and a second stage cyclone air outlet <b>124</b>. Each second stage cyclone chamber <b>120</b> also includes at least one dirt outlet <b>128</b>, through which dirt and debris that is separated from the air flow can exit the cyclone chamber <b>120</b>. While it is preferred that most or all of the dirt entrained in the air exiting the first cyclonic cleaning stage exits the second stage cyclone chambers via the dirt outlets <b>128</b>, some dirt may settle on the bottom end wall <b>130</b> of the cyclone chambers <b>120</b> and/or may be entrained in the air exiting the second stage cyclone chambers via the air outlets <b>124</b>.

In some embodiments, all or substantially all of the dirt entrained in the air exiting the first cyclonic cleaning stage may be removed from the airflow by the second cyclonic cleaning stage. This may, for example, obviate the need to provide a pre-motor filter in the surface cleaning apparatus <b>10</b>.

In the illustrated example, each second stage cyclone dirt outlet <b>128</b> is in the form of a slot bounded by the cyclone side wall <b>121</b> and the upper cyclone end wall <b>150</b>, and is located toward the upper end of the cyclone chamber <b>120</b>. Alternatively, the dirt outlet may be of any other suitable configuration, and may be provided at another location in the cyclone chamber, including, for example as an annular gap between the sidewall and an end wall of the cyclone chamber or an arrestor plate or other suitable member.

Preferably, each second stage cyclone air inlet <b>122</b> is located toward one end of the cyclone chamber <b>120</b> (the lower end in the illustrated example) and may be positioned adjacent the corresponding cyclone chamber end wall <b>130</b>. Alternatively, the cyclone air inlet <b>122</b> may be provided at another location within the second stage cyclone chamber <b>120</b>. Preferably, each air inlet <b>122</b> is positioned so that air flowing through the inlet and into a second stage cyclone chamber is travelling generally tangentially relative to, and preferably adjacent, the sidewall <b>121</b> of the cyclone chamber <b>120</b>.

The cross-sectional shape of the air inlet <b>122</b> can be any suitable shape. In the illustrated example each air inlet has a cross-sectional shape that is generally rectangular (rounded rectangular), having a height H_I_{<sub2>2 </sub2>}in the longitudinal direction (i.e. parallel to cyclone axis <b>125</b>) and a width W_I_{<sub2>2 </sub2>}in a transverse direction. The total cross-sectional area of the second stage air inlets (i.e. the sum of the cross-sectional areas of each inlet <b>122</b><i>a</i>-<i>f</i>) can be referred to as the total cross-sectional area or total flow area of the second cyclonic cleaning stage.

Referring to <figref idref="DRAWINGS">FIG. 12</figref>, each second stage cyclone chamber <b>120</b> has a height H_C_{<sub2>2 </sub2>}in the longitudinal direction (i.e. parallel to cyclone axis <b>125</b>). The height of each second stage cyclone chamber <b>120</b> is preferably selected such that air entering the cyclone chambers via inlets <b>122</b> is expected to rotate approximately 3 to 6 times, 3 to 5 times, 2 to 4 times or three-and-a-half times in each second stage cyclone chamber prior to exiting the cyclone chamber via outlet <b>124</b>. For example, the height H_C_{<sub2>2 </sub2>}of a second stage cyclone chamber <b>120</b> may be between 3 and 4 times, the height H_I_{<sub2>2 </sub2>}of a second stage cyclone air inlet <b>122</b>.

Air can exit each second stage cyclone chambers <b>120</b> via a second stage air outlet <b>124</b> provided for each cyclone chamber <b>120</b>. Preferably, the cyclone air outlets <b>124</b><i>a</i>-<i>f </i>are positioned in one of the end walls of each cyclone chamber <b>120</b> and, in the example illustrated, are positioned in the same ends as the air inlets <b>122</b><i>a</i>-<i>f</i>. In the illustrated embodiment the air outlets <b>124</b><i>a</i>-<i>f </i>are generally circular in cross-sectional shape. Preferably, the cross-sectional or flow area of each second stage cyclone air outlet <b>124</b> is generally equal to the flow area of the first stage cyclone air inlet <b>112</b> for its respective cyclone chamber. In the illustrated example, each cyclone air outlet <b>124</b> comprises a vortex finder <b>126</b>.

Height of Each Second Stage Cyclone Chamber Greater than the Height of Each First Stage Cyclone Chamber

The following is a description of the sizing of a second stage cyclone compared to a first stage cyclone that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein including the positioning of the dirt collection region for second stage cyclones, a dual opening latching mechanism and the connection of the second stage cyclone chamber air outlets with an upstream chamber of a pre-motor filter.

In order to reduce backpressure through the cyclone assembly <b>100</b>, it is preferred that the velocity of the airflow entering the first cyclonic cleaning stage is approximately equal to the velocity of the airflow entering the second cyclonic cleaning stage. That is, the airflow velocity through the first stage cyclone air inlet <b>112</b> may be approximately equal to the airflow velocity through each of the second stage cyclone air inlets <b>122</b>.

In an effort to achieve relatively equal airflow velocities, cyclone assembly <b>100</b> may be dimensioned so that the total cross-sectional area of the air inlet for the first cyclonic cleaning stage (i.e. the cross-sectional area of the air inlet <b>112</b> in the illustrated example) is approximately equal to the total cross-sectional area of the second stage air inlets (i.e. the sum of the cross-sectional areas of each inlet <b>122</b><i>a</i>-<i>f</i>).

However, due to boundary layer effects at the perimeter of the inlet, the effective cross-sectional area of each air inlet <b>112</b>, <b>122</b> may be smaller than the physical dimensions of the inlet. For example, a boundary layer having a thickness of about 0.005 to 0.010 inches may form around the perimeter of each air inlet, reducing the effective cross-sectional or flow area of that inlet. For example, for a rectangular air inlet of height H, width W, and assuming a constant boundary layer L_B, the effective cross sectional area for the inlet may be estimated as: &lt;br /&gt;Area_Effective=(<i>H</i>−(2<i>×L</i>_B))×(<i>W</i>−(2<i>×L</i>_B))=<i>HW−</i>2(<i>HL</i>_B<i>+WL</i>_B−2<i>L</i>_B²).

Where the second cyclonic cleaning stage has a larger number of second stage cyclones than the first cyclonic cleaning stage, as in the illustrated example, the total effective cross-sectional area of the second stage air inlets <b>122</b> may be reduced by a greater amount than that of the first stage air inlet <b>112</b> (as the boundary layer thickness at the perimeter of an inlet is typically not dependent on the area of the inlet). To adjust for this imbalance, the cross-sectional area of each second stage air inlet <b>122</b> is preferably increased by about 10 to 30%, and more preferably by about 15% over what would be required to provide an approximately equal physical inlet area to air inlet <b>112</b>. This may be achieved by varying the width and/or height of the second stage air inlets and preferably varying at least the height of the second stage air inlets. For example, the height of the second stage air inlets may be increased by about 10 to 30%, and more preferably by about 15%.

While the airflow velocity through the first stage cyclone air inlet <b>112</b> is preferably approximately equal to the airflow velocity through each of the second stage cyclone air inlets <b>122</b>, the separation characteristics of the first and second cyclonic cleaning stages may nonetheless be different. For example, since the second stage cyclone chambers <b>120</b> each have a smaller radius than the first stage cyclone chamber <b>110</b>, particles entrained in the airflow in the second stage cyclones will experience a greater centrifugal force than they experienced in the first stage cyclone, which may promote the dis-entrainment of smaller particles from the airflow in the second cyclonic cleaning stage.

In accordance with one feature, the height of each second stage cyclone chamber may be greater than the height of the first stage cyclone chamber. An example of such an arrangement is shown in <figref idref="DRAWINGS">FIGS. 4-6 and 9-13</figref>.

Since the second stage cyclone chambers <b>120</b> each have a smaller radius than the radius of the first stage cyclone chamber <b>110</b>, and since the width of an air inlet to a cyclone chamber is preferably a function of the cyclone chamber diameter, each second stage cyclone air inlet <b>122</b> preferably has a narrower width than that of the first stage inlet <b>112</b>. For example, an air stream entering a cyclone chamber may more or less maintain the same width as it travels through the cyclone chamber. Therefore, the radius of a cyclone chamber may be determined based on the width of the air stream (the width of the air inlet) and the width required for the return air steam travelling to the cyclone chamber air outlet (e.g., the width of a vortex finder). Therefore the radius of a cyclone chamber may be approximately equal to the width of the cyclone chamber air inlet, the width of the wall of the vortex finder and half the diameter of the vortex finder.

In certain preferred embodiments, without taking into account the decreased flow area due to boundary layer effects, the width W_I_{<sub2>2 </sub2>}for each inlet <b>122</b><i>a</i>-<i>f </i>may be within about +/−15% of the width W_I_{<sub2>1 </sub2>}for inlet <b>112</b> divided by the number of second stage cyclone chambers. For example, in the illustrated embodiment, there are six second stage cyclone chambers <b>120</b><i>a</i>-<i>f</i>, so the width W_I_{<sub2>2 </sub2>}for each inlet <b>122</b><i>a</i>-<i>f </i>is preferably about

<maths id="MATH-US-00002" num="00002"><math overflow="scroll"><mrow><mfrac><msub><mi>W</mi><msub><mi>I</mi><mn>1</mn></msub></msub><mn>6</mn></mfrac><mo>±</mo><mrow><mn>15</mn><mo>⁢</mo><mrow><mi>%</mi><mo>.</mo></mrow></mrow></mrow></math></maths>

As discussed above, the total cross-sectional area of the second stage air inlets (e.g. the sum of the cross-sectional areas of each inlet <b>122</b><i>a</i>-<i>f</i>) may be about 10-30% greater than the total cross-sectional area of the first cyclonic cleaning stage (e.g. the cross-sectional area of the air inlet <b>112</b>), so that the effective flow area of the second cyclonic cleaning stage is approximately equal to the effective flow area of the first cyclonic cleaning stage, after taking boundary layer effects at the air inlets into account.

In order to determine the height H_I_{<sub2>2 </sub2>}for each inlet <b>122</b>, the radius of the second stage cyclones may be first determined based on, e.g., the centrifugal forces to be imposed on an air stream travelling therein. The width of the cyclone chamber air inlet <b>122</b> may then be determined to be approximately equal to the radial thickness available in the cyclone chamber in which the air stream will rotate. Finally, the height H_I_{<sub2>2 </sub2>}for each inlet <b>122</b> may be determined based on the cross sectional area required to provide a cross-sectional flow area (taking into account boundary layer losses) that is approximately equal to the cross-sectional flow area of the first stage cyclone air inlet (taking into account boundary layer losses).

In certain other preferred embodiments, the height H_I_{<sub2>2 </sub2>}of each second stage cyclone chamber air inlet <b>122</b> is between about 1.25 to 2.5, 1.25 to 2, 1.25 to 1.75 times greater than the height H_I_{<sub2>1 </sub2>}of the inlet <b>112</b>.

As noted above, the height H_C_{<sub2>2 </sub2>}of a second stage cyclone chamber <b>120</b> is preferably between 3 to 6, 3 to 5, 3 to 4 and may be about 3.5 times the height H_I_{<sub2>2 </sub2>}of a second stage cyclone air inlet <b>122</b>, and the height H_C_{<sub2>1 </sub2>}of the first stage cyclone chamber <b>110</b> is preferably between 3 to 6, 3 to 5, 3 to 4 and may be about 3.5 times the height H_I_{<sub2>1 </sub2>}of the first stage cyclone air inlet <b>112</b>. Thus, since the height H_I_{<sub2>2 </sub2>}for each inlet <b>122</b> is preferably greater than H_I_{<sub2>1</sub2>}, the height H_C_{<sub2>1 </sub2>}of each second stage cyclone chamber <b>120</b> is preferably greater than the height H_C_{<sub2>1 </sub2>}of the first stage cyclone chamber <b>110</b>.

It will be appreciated that some of the embodiments disclosed herein may not use any of the features of the second stage cyclone chambers disclosed herein and that, in those embodiments, the second stage cyclone chambers may be of various constructions and that in those embodiments any second stage cyclone chamber known in the art may be used.

Dirt Collection Region for Second Stage Cyclones Positioned Above and Overlying the First Stage Cyclone

The following is a description of the positioning of the dirt collection region for second stage cyclones that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein including the sizing of a second stage cyclone compared to a first stage cyclone, a dual opening latching mechanism and the connection of the second stage cyclone chamber air outlets with an upstream chamber of a pre-motor filter.

In accordance with one feature, at least a portion of, and preferably most or substantially all of a second stage dirt collection region may be positioned longitudinally above and overlying the first stage cyclone chamber. In such an embodiment, this preferred location for the second stage dirt collection region may facilitate a more compact design of the cyclone assembly <b>100</b>.

Referring to <figref idref="DRAWINGS">FIG. 11</figref>, a first stage dirt collection chamber <b>119</b> is in communication with dirt outlet <b>118</b> to collect the dirt and debris as it exits first stage cyclone chamber <b>110</b>. Dirt collection chamber <b>119</b> may be of any suitable configuration. Referring to <figref idref="DRAWINGS">FIGS. 5 and 13</figref>, in the illustrated example, the dirt collection chamber <b>119</b> is bounded by outer sidewall <b>108</b>, first stage cyclone side wall <b>111</b>, lower end wall <b>130</b>, and intermediate wall <b>140</b>.

As shown in <figref idref="DRAWINGS">FIGS. 9 and 10</figref>, in use air enters the first stage cyclone chamber <b>110</b> via air inlet <b>112</b> and exits the chamber <b>110</b> via air outlet <b>114</b>, while separated dirt and debris exits the cyclone chamber <b>110</b> via dirt outlet <b>118</b>, where it collects in the first stage dirt collection chamber <b>119</b>.

To help facilitate emptying the dirt collection chamber <b>119</b>, at least one of or both of the end walls <b>130</b>, <b>140</b> may be openable. Preferably, end wall <b>130</b> is moveable between a closed position (<figref idref="DRAWINGS">FIG. 13</figref> and <figref idref="DRAWINGS">FIG. 7</figref>) and an open position (<figref idref="DRAWINGS">FIG. 8</figref>). When the end wall <b>130</b> is in the open position, the first stage dirt collection chamber <b>119</b> and the manifold <b>117</b> may be emptied concurrently. In addition, the second cyclone chambers are also opened so that the second cyclone chambers may also be concurrently openable. Optionally, it will be appreciated that the second stage cyclone chambers need not be opened, e.g., if the lower ends of the second stage cyclone chambers are not moveable with end wall <b>130</b>. Accordingly, the lower end walls of the dirt collection chamber <b>119</b> and/or the cyclone chamber <b>110</b> and/or the second stage cyclone chambers <b>120</b> need not be integral with each other, and the dirt collection chamber <b>119</b> and/or the cyclone chamber <b>110</b> and/or the second stage cyclone chambers <b>120</b> may be openable independently or in a sub-combination, e.g., the dirt collection chamber <b>119</b> and the cyclone chamber <b>110</b> may be openable independently of the second stage cyclone chambers <b>120</b> or the dirt collection chamber <b>119</b> and the second stage cyclone chambers <b>120</b> may be openable independently of the cyclone chamber <b>110</b>.

End wall <b>130</b> is preferably configured so that when it is in the closed position, the upper surface <b>132</b> cooperatively engages a lower surface of one or more of the sidewalls <b>108</b>, <b>111</b>, and <b>121</b><i>a</i>-<i>f</i>. For example, as shown in <figref idref="DRAWINGS">FIGS. 8 and 15</figref>, the upper surface <b>132</b> may have one or more channels or grooves <b>138</b> configured to receive the ends of sidewalls <b>108</b>, <b>111</b>, and <b>121</b><i>a</i>-<i>f </i>when the end wall <b>130</b> is in the closed position. Optionally, one or more sealing or gasketing elements may be provided between groove(s) <b>138</b> and the sidewall ends. Alternatively, the upper surface <b>132</b> may be relatively planar, and configured to abut the sidewalls <b>108</b>, <b>111</b>, and <b>121</b><i>a</i>-<i>f</i>, with or without gasketing elements.

Referring to <figref idref="DRAWINGS">FIG. 5</figref>, in the illustrated example, intermediate wall <b>140</b> acts as an upper end wall for both dirt collection chamber <b>119</b> and first stage cyclone chamber <b>110</b>. Wall <b>140</b> is moveable between a closed position (FIG. <b>13</b>) and an open position (<figref idref="DRAWINGS">FIG. 5</figref>). When the intermediate wall <b>140</b> is in the open position, the first stage cyclone chamber <b>110</b>, the first stage dirt collection chamber <b>119</b>, and the second stage cyclone chambers <b>120</b><i>a</i>-<i>f </i>can be emptied concurrently. Alternatively, the upper end walls of the dirt collection chamber <b>119</b> and/or the cyclone chamber <b>110</b> and/or the second stage cyclone chambers <b>120</b> need not be integral with each other, and the dirt collection chamber <b>119</b> and/or the cyclone chamber <b>110</b> and/or the second stage cyclone chambers <b>120</b> may be openable independently or in a sub-combination, e.g., the dirt collection chamber <b>119</b> and the cyclone chamber <b>110</b> may be openable independently of the second stage cyclone chambers <b>120</b> or the dirt collection chamber <b>119</b> and the second stage cyclone chambers <b>120</b> may be openable independently of the cyclone chamber <b>110</b>.

Wall <b>140</b> is preferably configured so that when it is in the closed position, the lower surface <b>144</b> cooperatively engages an upper surface of one or more of the sidewalls <b>108</b>, <b>111</b>, and <b>121</b><i>a</i>-<i>f</i>. For example, as shown in <figref idref="DRAWINGS">FIGS. 5 and 6</figref>, the lower surface <b>144</b> may have one or more channels or grooves <b>148</b> configured to receive the ends of sidewalls <b>108</b>, <b>111</b>, and <b>121</b><i>a</i>-<i>f </i>when the wall <b>140</b> is in the closed position. Optionally, one or more sealing or gasketing elements may be provided between groove(s) <b>148</b> and the sidewall ends. Alternatively, the lower surface <b>144</b> may be relatively planar, and configured to abut the sidewalls <b>108</b>, <b>111</b>, and <b>121</b><i>a</i>-<i>f</i>, with or without gasketing elements.

As exemplified in <figref idref="DRAWINGS">FIGS. 4 and 11</figref>, a second stage dirt collection chamber <b>129</b> may be associated with each second stage cyclone chamber <b>120</b>. As illustrated, each second stage dirt collection chamber <b>129</b><i>a</i>-<i>f </i>is in communication with a dirt outlet <b>128</b><i>a</i>-<i>f </i>of its respective cyclone chamber <b>120</b><i>a</i>-<i>f </i>to collect the dirt and debris as it exits that second stage cyclone chamber. Dirt collection chambers <b>129</b><i>a</i>-<i>f </i>may be of any suitable configuration. Referring to <figref idref="DRAWINGS">FIGS. 4 and 13</figref>, in the illustrated example, each dirt collection chamber <b>129</b> is bounded an upper sidewall extension <b>141</b>, intermediate wall <b>140</b>, upper end wall <b>150</b>, and one or more interior divider walls <b>145</b>.

Alternately, two or more second stage cyclone chambers <b>120</b> may be associated with a single second stage dirt collection chamber. Accordingly, for example, a single second stage dirt collection chamber may be provided. Collectively, the second stage dirt collection chamber(s) may be referred to generally as a second stage dirt collection region. Accordingly, while in the illustrated example each second stage cyclone chamber <b>120</b><i>a</i>-<i>f </i>has its own associated second stage dirt collection chamber <b>129</b><i>a</i>-<i>f</i>, this need not be the case. For example, fewer or no interior divider walls <b>145</b> may be provided, resulting in two or more second stage dirt outlets being in communication with a shared second stage dirt collection chamber.

As shown in <figref idref="DRAWINGS">FIGS. 9 and 10</figref>, in use air enters each second stage cyclone chamber <b>120</b><i>a</i>-<i>f </i>via an air inlet <b>122</b><i>a</i>-<i>f </i>and exits each chamber <b>120</b><i>a</i>-<i>f </i>via an air outlet <b>124</b><i>a</i>-<i>f</i>, while separated dirt and debris exits each cyclone chamber <b>120</b><i>a</i>-<i>f </i>via a dirt outlet <b>128</b><i>a</i>-<i>f</i>, where it collects in the second stage dirt collection region.

To help facilitate emptying the dirt collection chambers <b>129</b><i>a</i>-<i>f</i>, end wall <b>150</b> may be openable. Preferably, end wall <b>150</b> is moveable between a closed position (<figref idref="DRAWINGS">FIG. 13</figref> and <figref idref="DRAWINGS">FIG. 5</figref>) and an open position (<figref idref="DRAWINGS">FIG. 4</figref>). When the end wall <b>150</b> is in the open position, the second stage dirt collection chambers <b>129</b><i>a</i>-<i>f </i>can be emptied concurrently.

Notably, in the illustrated configuration, when the end wall <b>150</b> is in a closed position and the intermediate wall <b>140</b> is in the open position, as shown in <figref idref="DRAWINGS">FIG. 5</figref>, the first stage cyclone chamber <b>110</b>, the first stage dirt collection chamber <b>119</b>, and the second stage cyclone chambers <b>120</b><i>a</i>-<i>f </i>may be emptied concurrently, while the second stage dirt collection chambers <b>129</b><i>a</i>-<i>f </i>remain closed.

It will be appreciated that the second stage dirt collection region may be opened regardless of the position of the upper end <b>104</b> (i.e., whether intermediate wall <b>140</b> is open or closed).

It will be appreciated that some of the embodiments disclosed herein may not use any of the features of the dirt collection chambers disclosed herein and that, in those embodiments, the dirt collection chambers may be of various constructions and that in those embodiments any dirt collection chamber known in the art may be used.

Cyclone Assembly with Openable Ends

The following is a description of a cyclone assembly that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein including the sizing of a second stage cyclone compared to a first stage cyclone, and the connection of the second stage cyclone chamber air outlets with an upstream chamber of a pre-motor filter

<figref idref="DRAWINGS">FIGS. 23-29</figref> exemplify another embodiment of a cyclone assembly, referred to generally as <b>100</b>′. Cyclone assembly <b>100</b>′ may be used as an air treatment member to remove particulate matter (e.g. dirt, dust) from an air flow. Preferably, the cyclone assembly is removable from the surface cleaning apparatus. Providing a detachable cyclone assembly <b>100</b>′ may allow a user to carry the cyclone assembly <b>100</b>′ to a garbage can for emptying, without needing to carry or move the rest of the surface cleaning apparatus <b>10</b>. Preferably, the cyclone assembly is removable as a closed module, which may help prevent dirt and debris from spilling out of the cyclone assembly <b>100</b>′ during transport for emptying.

As exemplified in <figref idref="DRAWINGS">FIG. 23</figref>, the cyclone assembly <b>100</b> has a lower end <b>102</b>, an upper end <b>104</b>, and an outer sidewall <b>108</b>. Preferably, an assembly handle <b>106</b> is provided at the upper end <b>104</b>. The assembly handle <b>106</b> may facilitate carrying of the cyclone assembly when it is detached from the surface cleaning apparatus <b>10</b>.

Referring to <figref idref="DRAWINGS">FIGS. 23-29</figref>, cyclone assembly <b>100</b> includes a first cyclonic cleaning stage and a second cyclonic cleaning stage located downstream of the first cyclonic cleaning stage. The first cyclonic cleaning stage includes a first stage cyclone chamber <b>110</b>′ that extends along a cyclone axis <b>115</b>′ and includes a sidewall <b>111</b>′, which may be generally cylindrical, extending between a lower end wall <b>113</b>′ and an upper end wall <b>150</b>′. In the illustrated embodiment, the first stage cyclone chamber <b>110</b>′ is arranged in a generally vertical, inverted cyclone orientation. Alternatively, the first stage cyclone chamber may be provided in another orientation, for example as a horizontal or inclined cyclone and may be of any cyclone configuration. Alternately, or in addition, the first cyclonic cleaning stage may comprise a plurality of cyclone chambers.

In the illustrated embodiment, the first stage cyclone chamber <b>110</b>′ includes a first stage cyclone air inlet <b>112</b>′ and a first stage cyclone air outlet <b>114</b>′. First stage cyclone chamber <b>110</b>′ also includes at least one dirt outlet <b>118</b>′, through which dirt and debris that is separated from the air flow can exit the cyclone chamber <b>110</b>′. While it is preferred that most or all of the dirt exit the first stage cyclone chamber via the dirt outlet <b>118</b>′, some dirt may settle on the bottom end wall <b>113</b>′ of the cyclone chamber <b>110</b>′ and/or may be entrained in the air exiting the first stage cyclone chamber via the air outlet <b>114</b>′.

In the illustrated example, the first stage cyclone dirt outlet <b>118</b>′ is in the form of a slot bounded by the cyclone side wall <b>111</b>′ and the upper cyclone end wall <b>150</b>′, and is located toward the upper end of the cyclone chamber <b>110</b>′. Alternatively, the dirt outlet may be of any other suitable configuration, including, for example as an annular gap between the sidewall and an end wall of the cyclone chamber or a plate or other suitable member extending towards or into the open upper end of the cyclone chamber <b>110</b>′.

Preferably, the first stage cyclone air inlet <b>112</b>′ is located toward the end of the cyclone chamber <b>110</b>′ spaced from the end with the dirt outlet (the lower end in the illustrated example) and may be positioned adjacent the corresponding cyclone chamber end wall <b>113</b>′. Preferably, the air inlet <b>112</b>′ is positioned so that air flowing through the inlet and into the first stage cyclone chamber is travelling generally tangentially relative to, and preferably adjacent, the sidewall <b>111</b>′ of the cyclone chamber <b>110</b>′.

The cross-sectional shape of the air inlet <b>112</b>′ may be any suitable shape. In the illustrated example of <figref idref="DRAWINGS">FIG. 24</figref>, the air inlet has a cross-sectional shape that is generally rectangular (e.g., it has rounded corners and can be referred to as a rounded rectangle). The cross-sectional area of the air inlet <b>112</b>′ may be referred to as the cross-sectional area or flow area of the first stage cyclone air inlet <b>112</b>′. Alternatively, instead of being a rounded rectangle, the cross-sectional shape of the air inlet may be another shape, including, for example, round, oval, square and rectangular.

Referring to <figref idref="DRAWINGS">FIG. 25</figref>, the first stage cyclone chamber <b>110</b>′ has a height in the longitudinal direction (i.e. parallel to cyclone axis <b>115</b>′), being the distance between the lower end wall <b>113</b>′ and upper end wall <b>150</b>′. The height of the first stage cyclone chamber <b>110</b>′ is preferably selected such that air entering the cyclone chamber via inlet <b>112</b>′ is expected to rotate approximately 3 to 6 times, 3 to 5 times, 2 to 4 times or three-and-a-half times in the first stage cyclone chamber prior to exiting the cyclone chamber via outlet <b>114</b>′.

In general, it may be assumed that the airflow against the cyclone chamber sidewall as it progresses around the cyclone chamber maintains a degree of cohesion, and that during each revolution within a cyclone chamber, an air stream moves in the longitudinal direction towards an end of the cyclone chamber by a distance approximately equal to the height of the cyclone chamber air inlet. For example, in a cyclone chamber that has a longitudinal height that is five times greater than the longitudinal height of its air inlet, the resulting cyclone may be expected to rotate about five times as it travels from the end of the cyclone chamber that has the air inlet to the opposite end of the cyclone chamber.

Thus, in order to promote the formation of a cyclone that is expected to rotate about three-and-a-half times in the first stage cyclone chamber <b>110</b>′, the height of the first stage cyclone chamber <b>110</b>′ may be between 3 and 4 times the height of the first stage cyclone air inlet <b>112</b>′.

Air may exit the first stage cyclone chamber <b>110</b>′ via the first stage air outlet <b>114</b>′. Preferably, the cyclone air outlet is positioned in one of the cyclone chamber end walls and, in the example illustrated, is positioned in the same end as the air inlet <b>112</b>′ and air inlet <b>112</b>′ may be positioned adjacent or at the end wall <b>113</b>′. As exemplified, the air outlet <b>114</b>′ may be generally circular in cross-sectional shape. Preferably, the cross-sectional or flow area of the first stage cyclone air outlet <b>114</b>′ is generally equal to the flow area of the first stage cyclone air inlet <b>112</b>′. In the illustrated example, the cyclone air outlet <b>114</b>′ comprises a vortex finder <b>116</b>′.

Air exiting the first stage air outlet <b>114</b>′ may be directed into a chamber or manifold <b>117</b>′. From there, the air is directed into the second cyclonic cleaning stage through one or more air flow passages. The second cyclonic cleaning stage includes a plurality of second stage cyclone chambers <b>120</b>′ arranged in parallel. In the illustrated embodiment, two second stage cyclone chambers are shown, referred to as <b>120</b><i>a</i>′ and <b>120</b><i>b</i>′, respectively.

In the illustrated embodiment, each second stage cyclone chamber <b>120</b>′ is arranged in a generally vertical, inverted cyclone orientation. Alternatively, the second stage cyclone chambers can be provided in another orientation, for example as horizontal or inclined cyclones and may be of any cyclone configuration.

In the illustrated embodiment, each second stage cyclone chamber extends along a respective cyclone axis <b>125</b>′ (see e.g. <figref idref="DRAWINGS">FIG. 25</figref>) and extends between a lower end wall or bottom <b>131</b><i>a</i>′, <b>131</b><i>b</i>′ and an upper end wall <b>150</b>′. In the illustrated embodiment, each second stage cyclone chamber is bounded by a sidewall <b>121</b><i>a</i>′, <b>121</b><i>b′. </i>

In the illustrated embodiment, each second stage cyclone chamber <b>120</b>′ includes an airflow passage <b>123</b>′ extending from manifold <b>117</b>′ to a second stage cyclone air inlet <b>122</b>′ and a second stage cyclone air outlet <b>124</b>′. Each second stage cyclone chamber <b>120</b>′ also includes at least one dirt outlet <b>128</b>′, through which dirt and debris that is separated from the air flow can exit the cyclone chamber <b>120</b>′. While it is preferred that most or all of the dirt entrained in the air exiting the first cyclonic cleaning stage exits the second stage cyclone chambers via the dirt outlets <b>128</b>′, some dirt may settle on the bottom end wall <b>131</b>′ of the cyclone chambers <b>120</b>′ and/or may be entrained in the air exiting the second stage cyclone chambers via the air outlets <b>124</b>′.

In some embodiments, all or substantially all of the dirt entrained in the air exiting the first cyclonic cleaning stage may be removed from the airflow by the second cyclonic cleaning stage. This may, for example, obviate the need to provide a pre-motor filter in the surface cleaning apparatus <b>10</b>.

In the illustrated example, each second stage cyclone dirt outlet <b>128</b>′ is in the form of a slot bounded by the cyclone side wall <b>121</b>′ and the upper cyclone end wall <b>150</b>′, and is located toward the upper end of the cyclone chamber <b>120</b>′. Alternatively, the dirt outlet may be of any other suitable configuration, including, for example, as an annular gap between the sidewall and an end wall of the cyclone chamber or a plate or other suitable member extending towards or into the open upper end of the cyclone chamber <b>120</b>′.

Preferably, each second stage cyclone air inlet <b>122</b>′ is located toward the end of the cyclone chamber <b>120</b>′ spaced from the end with the dirt outlet (the lower end in the illustrated example) and may be positioned adjacent the corresponding cyclone chamber end wall <b>131</b>′. Alternatively, the cyclone air inlet <b>122</b>′ may be provided at another location within the second stage cyclone chamber <b>120</b>′. Preferably, each air inlet <b>122</b>′ is positioned so that air flowing through the inlet and into a second stage cyclone chamber is travelling generally tangentially relative to, and preferably adjacent, the sidewall <b>121</b>′ of that cyclone chamber <b>120</b>′.

The cross-sectional shape of the air inlet <b>122</b>′ may be any suitable shape. In the illustrated example each air inlet has a cross-sectional shape that is generally rectangular, having a height in the longitudinal direction (i.e. parallel to cyclone axis <b>125</b>′) and a width in a transverse direction. The total cross-sectional area of the second stage air inlets (i.e. the sum of the cross-sectional areas of each inlet <b>122</b><i>a</i>′, <b>122</b><i>b</i>′) may be referred to as the total cross-sectional area or total flow area of the second cyclonic cleaning stage.

Referring to <figref idref="DRAWINGS">FIGS. 25 and 28</figref>, each second stage cyclone chamber <b>120</b>′ has a height in the longitudinal direction (i.e. parallel to cyclone axis <b>125</b>′). The height of each second stage cyclone chamber <b>120</b>′ is preferably selected such that air entering the cyclone chambers via inlets <b>122</b>′ is expected to rotate approximately 3 to 6 times, 3 to 5 times, 2 to 4 times or three-and-a-half times in each second stage cyclone chamber prior to exiting the cyclone chamber via outlet <b>124</b>′. For example, the height of a second stage cyclone chamber <b>120</b>′ may be between 3 and 4 times the height of a second stage cyclone air inlet <b>122</b>′.

Air may exit each second stage cyclone chambers <b>120</b>′ via a second stage air outlet <b>124</b>′ provided for each cyclone chamber <b>120</b>′. In the illustrated example, corresponding ports <b>127</b><i>a</i>′, <b>127</b><i>b</i>′ are provided in end wall <b>130</b>′ to allow air to exit the cyclone assembly <b>100</b>′. Preferably, the cyclone air outlets <b>124</b><i>a</i>-<i>b</i>′ are positioned in one of the end walls of each cyclone chamber <b>120</b>′ and, in the example illustrated, are positioned in the same ends as the air inlets <b>122</b><i>a</i>-<i>b</i>′. As exemplified, the air outlets <b>124</b><i>a</i>-<i>b</i>′ may be generally circular in cross-sectional shape. Preferably, the cross-sectional or flow area of each second stage cyclone air outlet <b>124</b>′ is generally equal to the flow area of the second stage cyclone air inlet <b>122</b>′ for its respective cyclone chamber. In the illustrated example, each cyclone air outlet <b>124</b>′ comprises a vortex finder <b>126</b>′.

Referring to <figref idref="DRAWINGS">FIGS. 25 and 26</figref>, a first stage dirt collection chamber <b>119</b>′ is in communication with dirt outlet <b>118</b>′ to collect the dirt and debris as it exits first stage cyclone chamber <b>110</b>′. Dirt collection chamber <b>119</b>′ may be of any suitable configuration. In the illustrated example, the dirt collection chamber <b>119</b>′ is bounded by outer sidewall <b>108</b>′, first stage cyclone side wall <b>111</b>′, lower end wall <b>130</b>′, and upper end wall <b>150</b>′.

In use, air enters the first stage cyclone chamber <b>110</b>′ via air inlet <b>112</b>′ and exits the chamber <b>110</b>′ via air outlet <b>114</b>′, while separated dirt and debris exits the cyclone chamber <b>110</b>′ via dirt outlet <b>118</b>′, where it collects in the first stage dirt collection chamber <b>119</b>′.

To help facilitate emptying the dirt collection chamber <b>119</b>′, at least one of or both of the end walls <b>130</b>′, <b>150</b>′ may be openable. Preferably, end wall <b>130</b>′ is moveable between a closed position (e.g. <figref idref="DRAWINGS">FIG. 27</figref>) and an open position (e.g. <figref idref="DRAWINGS">FIG. 28</figref>). When the end wall <b>130</b>′ is in the open position, the first stage dirt collection chamber <b>119</b>′ and the manifold <b>117</b>′ may be emptied concurrently. In addition, the air flow passages <b>123</b>′ from manifold <b>117</b>′ to the second cyclone air inlets <b>122</b>′ are also opened so that the air flow passages <b>123</b>′ may also be concurrently openable. Optionally, it will be appreciated that the air flow passages to the second stage cyclone chambers need not be opened, e.g., if the lower ends of the air flow passages <b>123</b>′ are not moveable with end wall <b>130</b>′.

Also, when the end wall <b>130</b>′ is in the open position, in the illustrated example the second cyclone chambers are not opened. Optionally, it will be appreciated that the second stage cyclone chambers may be opened concurrently with one or more of the first stage dirt collection chamber <b>119</b>′, the air flow passages <b>123</b>′ and manifold <b>117</b>′, e.g., if the lower ends of the second stage cyclone chambers are moveable with end wall <b>130</b>′ (e.g., the lower ends of the second stage cyclone chambers <b>119</b>′, the lower end of the air flow passages <b>123</b>′ and the lower end of the manifold <b>117</b>′ are part of the end wall <b>130</b>′). Accordingly, the lower end walls of the dirt collection chamber <b>119</b>′, the air flow passages <b>123</b>′, the manifold <b>117</b>′ and the second stage cyclone chambers <b>120</b><i>a</i>′, <b>120</b><i>b</i>′ may be integral with each other. Alternately, the lower end walls of the dirt collection chamber <b>119</b>′ and/or the cyclone chamber <b>110</b>′ and/or the second stage cyclone chambers <b>120</b>′ and/or the air flow passages <b>123</b>′ and/or the manifold <b>117</b>′ need not be integral with each other, and the dirt collection chamber <b>119</b>′ and/or the cyclone chamber <b>110</b>′ and/or the second stage cyclone chambers <b>120</b>′ and/or the air flow passages <b>123</b>′ and/or the manifold <b>117</b>′ may be openable independently or in a sub-combination, e.g., the dirt collection chamber <b>119</b>′ may be openable independently of the second stage cyclone chambers <b>120</b>′.

End wall <b>130</b>′ is preferably configured so that when it is in the closed position, the upper surface <b>132</b>′ cooperatively engages a lower surface of one or more of the sidewalls <b>108</b>′, and <b>121</b><i>a</i>′, <b>121</b><i>b</i>′. For example, as shown in <figref idref="DRAWINGS">FIG. 28</figref>, the upper surface <b>132</b>′ may have one or more channels or grooves <b>138</b>′ configured to receive the ends of sidewalls <b>108</b>′, and <b>121</b><i>a</i>′, <b>121</b><i>b</i>′ when the end wall <b>130</b>′ is in the closed position. Optionally, one or more sealing or gasketing elements may be provided between groove(s) <b>138</b>′ and the sidewall ends. Alternatively, the upper surface <b>132</b>′ may be relatively planar, and configured to abut the sidewalls <b>108</b>′, and <b>121</b><i>a</i>′, <b>121</b><i>b</i>′, with or without gasketing elements.

As exemplified in <figref idref="DRAWINGS">FIGS. 25 and 26</figref>, a second stage dirt collection chamber <b>129</b>′ may be associated with each second stage cyclone chamber <b>120</b>′. As illustrated, each second stage dirt collection chamber <b>129</b><i>a</i>′, <b>129</b><i>b</i>′ is in communication with a dirt outlet <b>128</b><i>a</i>′, <b>128</b><i>b</i>′ of its respective cyclone chamber <b>120</b><i>a</i>′, <b>120</b><i>b</i>′ to collect the dirt and debris as it exits that second stage cyclone chamber. Dirt collection chambers <b>129</b><i>a</i>′, <b>129</b><i>b</i>′ may be of any suitable configuration. In the illustrated example, dirt collection chamber <b>129</b><i>a</i>′ is bounded by an upper portion of sidewall <b>121</b><i>a</i>′, an intermediate wall <b>140</b><i>a</i>′, upper end wall <b>150</b>′, an interior divider wall <b>145</b><i>a</i>′, and sidewall <b>111</b>′ of the cyclone chamber <b>110</b>′. Also, in the illustrated example, dirt collection chamber <b>129</b><i>b</i>′ is bounded by an upper portion of sidewall <b>121</b><i>b</i>′, an intermediate wall <b>140</b><i>b</i>′, upper end wall <b>150</b>′, an interior divider wall <b>145</b><i>b</i>′, and sidewall <b>108</b>′.

Alternately, two or more second stage cyclone chambers <b>120</b>′ may be associated with a single second stage dirt collection chamber. Accordingly, for example, a single second stage dirt collection chamber may be provided. Collectively, the second stage dirt collection chamber(s) may be referred to generally as a second stage dirt collection region. Accordingly, while in the illustrated example each second stage cyclone chamber <b>120</b><i>a</i>′, <b>120</b><i>b</i>′ has its own associated second stage dirt collection chamber <b>129</b><i>a</i>′, <b>120</b><i>b</i>′, this need not be the case. For example, dirt outlet <b>128</b><i>b</i>′ may be provided such that it faces towards dirt collection chamber <b>129</b><i>a</i>′ (e.g. on the opposite side of second stage cyclone chamber <b>120</b><i>b</i>′ as shown), resulting in two or more second stage dirt outlets being in communication with a shared second stage dirt collection chamber.

In use, air enters each second stage cyclone chamber <b>120</b><i>a</i>′, <b>120</b><i>b</i>′ via an air inlet <b>122</b><i>a</i>′, <b>122</b><i>b</i>′ and exits each chamber <b>120</b><i>a</i>′, <b>120</b><i>b</i>′ via an air outlet <b>124</b><i>a</i>′, <b>124</b><i>b</i>′, while separated dirt and debris exits each cyclone chamber <b>120</b><i>a</i>′, <b>120</b><i>b</i>′ via a dirt outlet <b>128</b><i>a</i>′, <b>128</b><i>b</i>′, where it collects in the second stage dirt collection region.

It will be appreciated that the lower wall of one or more second stage dirt collection chamber <b>129</b><i>a</i>′, <b>120</b><i>b</i>′ may be moveable with, and may be intergrally formed with, end wall <b>130</b>′ such that the second stage dirt collection chambers may be openable with one or more of the dirt collection chamber <b>119</b>′, the cyclone chamber <b>110</b>′, the second stage cyclone chambers <b>120</b>′ and the air flow passages <b>123</b>′ and/or the manifold <b>117</b>′.

Referring to <figref idref="DRAWINGS">FIG. 25</figref>, in the illustrated example, upper end wall <b>150</b>′ acts as an upper end wall for each of dirt collection chamber <b>119</b>′, first stage cyclone chamber <b>110</b>′, second stage cyclones <b>120</b><i>a</i>′, <b>120</b><i>b</i>′, and second stage dirt collection chambers <b>129</b><i>a</i>′, <b>129</b><i>b</i>′. Wall <b>150</b>′ is moveable between a closed position (e.g. <figref idref="DRAWINGS">FIG. 23</figref>) and an open position (e.g. <figref idref="DRAWINGS">FIG. 25</figref>). When the upper end wall <b>150</b>′ is in the open position, the first stage cyclone chamber <b>110</b>′, the first stage dirt collection chamber <b>119</b>′, the second stage cyclone chambers <b>120</b><i>a</i>′, <b>120</b><i>b</i>′, and the second stage dirt collection chambers <b>129</b><i>a</i>′, <b>129</b><i>b</i>′ can be emptied concurrently.

Wall <b>150</b>′ is preferably configured so that when it is in the closed position, the lower surface <b>154</b>′ cooperatively engages an upper surface of one or more of the sidewalls <b>108</b>′, <b>111</b>′, and <b>121</b><i>a</i>′, <b>121</b><i>b</i>′. For example, as shown in <figref idref="DRAWINGS">FIG. 25</figref>, the lower surface <b>154</b>′ may have one or more channels or grooves <b>158</b>′ configured to receive the ends of sidewalls <b>108</b>′, <b>111</b>′, and <b>121</b><i>a</i>′, <b>121</b><i>b</i>′ when the wall <b>150</b>′ is in the closed position. Optionally, one or more sealing or gasketing elements may be provided between groove(s) <b>158</b>′ and the sidewall ends. Alternatively, the lower surface <b>154</b>′ may be relatively planar, and configured to abut the sidewalls <b>108</b>′, <b>111</b>′, and <b>121</b><i>a</i>′, <b>121</b><i>b</i>′, with or without gasketing elements.

As discussed previously, in the illustrated example dirt collection chamber <b>129</b><i>a</i>′ is bounded by an upper portion of sidewall <b>121</b><i>a</i>′, an intermediate wall <b>140</b><i>a</i>′, upper end wall <b>150</b>′, an interior divider wall <b>145</b><i>a</i>′, and sidewall <b>111</b>′ of the cyclone chamber <b>110</b>′, and dirt collection chamber <b>129</b><i>b</i>′ is bounded by an upper portion of sidewall <b>121</b><i>b</i>′, an intermediate wall <b>140</b><i>b</i>′, upper end wall <b>150</b>′, an interior divider wall <b>145</b><i>b</i>′, and sidewall <b>108</b>′. Alternatively, one or both of intermediate walls <b>140</b><i>a</i>′, <b>140</b><i>b</i>′ may not be provided. For example, if intermediate wall <b>140</b><i>a</i>′ is not provided, dirt collection chamber <b>129</b><i>a</i>′ may be bounded by sidewall <b>121</b><i>a</i>′, upper end wall <b>150</b>′, an interior divider wall <b>145</b><i>a</i>′, sidewall <b>111</b>′ of the cyclone chamber <b>110</b>′, and lower end wall <b>130</b>′. Similarly, if intermediate wall <b>140</b><i>b</i>′ is not provided, dirt collection chamber <b>129</b><i>b</i>′ may be bounded by sidewall <b>121</b><i>b</i>′, upper end wall <b>150</b>′, interior divider wall <b>145</b><i>b</i>′, sidewall <b>108</b>′, and lower end wall <b>130</b>′.

An advantage of a configuration in which one or both of intermediate walls <b>140</b><i>a</i>′, <b>140</b><i>b</i>′ are not provided is that when the end wall <b>130</b>′ is in the open position, one or both of second stage dirt collection chambers <b>129</b><i>a</i>′, <b>129</b><i>b</i>′ may be emptied concurrently with the first stage dirt collection chamber <b>119</b>′, the manifold <b>117</b>′, and/or the air flow passages <b>123</b>′ from manifold <b>117</b>′ to the second cyclone air inlets <b>122</b><i>a</i>′, <b>122</b><i>b</i>′. Alternatively, instead of not providing intermediate walls <b>140</b><i>a</i>′, <b>140</b><i>b</i>′, one or more holes, slots or other apertures may be provided in one or both of intermediate walls <b>140</b><i>a</i>′, <b>140</b><i>b</i>′ to allow some or all of the dirt collected in dirt collection chambers <b>129</b><i>a</i>′, <b>129</b><i>b</i>′ to be emptied when the end wall <b>130</b>′ is in the open position.

Latching Mechanism

The following is a description of a dual opening latching mechanism that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein including the sizing of a second stage cyclone compared to a first stage cyclone, the positioning of a dirt collection region for second stage cyclones and the connection of the second stage cyclone chamber air outlets with an upstream chamber of a pre-motor filter.

In accordance with this feature, a latching mechanism with a multi-position switch or release mechanism may be provided to selectively retain the intermediate wall <b>140</b> and/or the upper end wall <b>150</b> in its respective closed position. An advantage of this design is that it may prevent a user from inadvertently opening both the intermediate wall <b>140</b> and the upper end wall <b>150</b> at the same time.

As exemplified in <figref idref="DRAWINGS">FIGS. 16-22</figref>, a latching mechanism, referred to generally as <b>200</b>, is provided between the intermediate wall <b>140</b> and the upper end wall <b>150</b>. Latching mechanism <b>200</b> includes an upper latch for selectively retaining upper end wall <b>150</b> in its closed position, and a lower latch for selectively retaining intermediate end wall <b>140</b> in its closed position. A release switch <b>260</b> is provided for selectively disengaging the upper latch or the lower latch.

Release switch <b>260</b> is an actuator that is moveable in two different directions, (e.g., left and right). When the actuator is moved in a first direction, a first locking member is moved to an unlocked position while a second locking member is maintained in a locked position. When the actuator is moved in a second direction, which may be an opposite direction to the first direction, the second locking member is moved to an unlocked position while the first locking member is maintained in a locked position. It will be appreciated that the first and second locking members may be separate elements or they may be opposite ends of a single linkage.

As exemplified in <figref idref="DRAWINGS">FIGS. 17, 19, and 22</figref>, the upper latch includes a generally U-shaped latching bar <b>220</b> that is pivotally coupled to a shaft <b>210</b>. Shaft <b>210</b> is parallel to both the intermediate wall <b>140</b> and the upper end wall <b>150</b>. The upper end of the latching bar <b>220</b> has a downwardly facing surface <b>224</b> that is configured to engage with a lip or flange <b>225</b> extending from the upper end wall <b>150</b> to cooperatively retain the end wall <b>150</b> in its closed position. When the latching bar <b>220</b> is in a locked position (as shown in <figref idref="DRAWINGS">FIGS. 17 and 22</figref>) and upper end wall <b>150</b> in its closed position, downwardly facing surface <b>224</b> overlies flange <b>225</b>, thereby retaining upper end wall <b>150</b> in its closed position. Preferably, latching bar <b>220</b> is biased towards its locked position, for example, using a spring or other biasing member(s) (not shown).

The upper end of the latching bar <b>220</b> also has an upwardly facing angled or beveled surface <b>222</b> that is configured to pivot the latching bar <b>220</b> away from the locked position when engaged by an angled or beveled surface <b>223</b> of flange <b>225</b>, thereby allowing the upper latch to be engaged by bringing the end wall <b>150</b> to its closed position.

Latching bar <b>220</b> also has a flange or projection <b>226</b> that extends generally forwardly. As shown in <figref idref="DRAWINGS">FIG. 17</figref>, projection <b>226</b> is angled or sloped such that one lateral end of the projection <b>226</b> extends further forward than the opposite lateral end.

As exemplified in <figref idref="DRAWINGS">FIGS. 19, 21, and 22</figref>, the lower latch includes a latching bar <b>240</b> that is also pivotally coupled to shaft <b>210</b>. The lower end of latching bar <b>240</b> has an upwardly facing surface <b>244</b> that is configured to engage with a lip or flange <b>245</b> extending from the outer sidewall <b>108</b> to cooperatively retain the intermediate wall <b>140</b> in its closed position. When the latching bar <b>240</b> is in a locked position (as shown in <figref idref="DRAWINGS">FIGS. 19 and 21</figref>) and intermediate wall <b>140</b> in its closed position, upwardly facing surface <b>244</b> overlies flange <b>245</b>, thereby retaining intermediate wall <b>140</b> in its closed position. Preferably, latching bar <b>240</b> is biased towards its locked position, for example, using a spring or other biasing member(s) (not shown).

The lower end of the latching bar <b>240</b> also has a downwardly facing angled or beveled surface <b>242</b> that is configured to pivot the latching bar <b>240</b> away from its locked position when engaged by an angled or beveled surface <b>243</b> of flange <b>245</b>, thereby allowing the lower latch to be engaged by bringing the intermediate wall <b>140</b> to its closed position.

Latching bar <b>240</b> also has a flange or projection <b>246</b> that extends generally forwardly. As exemplified in <figref idref="DRAWINGS">FIGS. 17 and 21</figref>, projection <b>246</b> is angled or sloped such that one lateral end of the projection <b>246</b> extends further forward than the opposite lateral end. Notably, projections <b>246</b> and <b>226</b> are angled in opposite directions. This arrangement facilitates the selective unlatching of either the upper or lower latch using a single multi-position switch or release mechanism.

As exemplified in <figref idref="DRAWINGS">FIG. 16</figref>, the release switch <b>260</b> for latching mechanism <b>200</b> is rotatably or pivotally coupled to a shaft <b>270</b>. Shaft <b>270</b> is generally perpendicular to both the intermediate wall <b>140</b> and the upper end wall <b>150</b>. Release switch <b>260</b> also includes an outwardly facing projection or tab <b>262</b> to facilitate a user's rotation of switch <b>260</b> about shaft <b>270</b>. Release switch <b>260</b> also includes an inwardly facing flange or projection <b>264</b> that is configured to engage the projections <b>226</b>, <b>246</b> of the upper and lower latching bars <b>220</b>, <b>240</b>, respectively.

As exemplified in <figref idref="DRAWINGS">FIGS. 16, 17 and 21</figref>, the release switch <b>260</b> is shown in a neutral position. In this position, inwardly facing projection <b>264</b> is not in contact with either projection <b>226</b> or projection <b>246</b>. As the release switch <b>260</b> is pivoted towards the position shown in <figref idref="DRAWINGS">FIG. 18</figref>, projection <b>264</b> is brought into abutment with projection <b>226</b> of the upper latching mechanism. Further pivoting of release switch <b>260</b> forces the upper latching bar <b>220</b> away from its locked position, and thereby unlatching the upper latch (as shown in <figref idref="DRAWINGS">FIG. 19</figref>) and permitting the upper end wall <b>150</b> to be moved to an open position.

Alternatively, if the release switch <b>260</b> is pivoted towards the position shown in <figref idref="DRAWINGS">FIG. 20</figref>, projection <b>264</b> is brought into abutment with projection <b>246</b> of the lower latching mechanism. Further pivoting of release switch <b>260</b> forces the lower latching bar <b>240</b> away from its locked position, and thereby unlatching the lower latch (as shown in <figref idref="DRAWINGS">FIG. 22</figref>) and permitting the intermediate wall <b>140</b> to be moved to an open position.

It will be appreciated that some of the embodiments disclosed herein may not use any of the features of the latching mechanisms disclosed herein and that, in those embodiments, mechanisms for retaining the intermediate and upper walls in their closed positions may be of various constructions and that in those embodiments any latching or retaining mechanism known in the art may be used.

Air Outlets for Second Stage Cyclones Provided in a Wall of Common Manifold, which May be a Pre-Motor Filter Chamber

The following is a description of the connection of the second stage cyclone chamber air outlets with an upstream chamber of a pre-motor filter for the second cyclonic cleaning that may be used by itself in any surface cleaning apparatus or in any combination or sub-combination with any other feature or features disclosed herein including the sizing of a second stage cyclone compared to a first stage cyclone, the positioning of a dirt collection region for second stage cyclones and a dual opening latching mechanism.

In accordance with this feature, the air outlets of a plurality of cyclone chambers that are connected in parallel may be connected directly to an upstream pre-motor filter chamber or manifold. Accordingly, some or all of the air outlets may extend to opening provided in the manifold. Accordingly, a manifold for the air outlets, which is upstream from the pre-motor filter chamber, is not provided.

Optionally, the upstream pre-motor filter chamber or manifold may be positioned in facing relationship with the air outlets of a plurality of cyclone chambers that are connected in parallel. Accordingly, the upstream face of the pre-motor filter may be positioned generally transverse to the axis of the cyclone air outlets, and the axis of the cyclone air outlets may be generally parallel to the cyclone of which they are the air exits. Therefore, for example, the manifold may be positioned below a second cyclonic cleaning stage and each of the second stage cyclone air outlets may have an outlet end in a wall of the chamber or manifold. An advantage of this design is that fewer conduit walls and/or ducting may be required to direct airflow from the second cyclonic cleaning stage towards the suction unit, which may simplify the design and/or construction of the cyclone assembly and/or surface cleaning apparatus, and/or may reduce backpressure through the surface cleaning apparatus.

As exemplified in <figref idref="DRAWINGS">FIGS. 9-11</figref>, air exiting the second stage air outlets <b>124</b><i>a</i>-<i>f </i>is directed into a chamber or header or manifold <b>27</b> bounded by the lower surface <b>134</b> of the lower end wall <b>130</b> of cyclone assembly <b>100</b> and the upper end of the suction unit <b>20</b>. From there, the air is directed by the suction motor through the suction unit <b>20</b> and subsequently exhausted out through the clean air outlet <b>18</b>.

In alternative embodiments, cyclone assembly <b>100</b> may include one or more additional manifolds downstream of the second stage air outlets <b>124</b><i>a</i>-<i>f </i>so that cyclone assembly <b>100</b> has a single assembly air outlet or fewer air outlets than there are second stage cyclone chambers.

As exemplified, the chamber or header or manifold is a pre-motor filter chamber that houses a pre-motor filter. In such a construction, the pre-motor filter chamber may be opened when the cyclone bin assembly is removed. For example, the cyclone bin assembly may form part of the pre-motor filter chamber (e.g., an upstream wall of the pre-motor filter chamber). An advantage of this design is that the pre-motor filter chamber is opened when the cyclone bin assembly is removed. Accordingly, when a user removes the cyclone bin assembly (e.g. to empty the dirt collection chamber(s)), the user may also inspect the condition of the pre-motor filter. The pre-motor filter may be any suitable type of porous filter media, such as a foam filter and/or a felt filter, or any other suitable pre-motor porous filter media(s) known in the art. Preferably, the pre-motor filter is removable to allow a user to clean and/or replace the filter when it is dirty.

Typically, a pre-motor filter is provided to prevent particulate matter that is not removed from the airstream by the cyclonic cleaning stages from being drawn into the suction motor. Otherwise, this unremoved particulate matter may cause damage to (or otherwise impair) the suction motor.

While the use of a pre-motor filter may be effective at protecting the suction motor, there may be one or more disadvantages. For example, the pre-motor filter may become clogged with particulate matter, requiring a user to clean and/or replace the filter, a task a user may regard as undesirable.

As used herein, the wording “and/or” is intended to represent an inclusive—or. That is, “X and/or Y” is intended to mean X or Y or both, for example. As a further example, “X, Y, and/or Z” is intended to mean X or Y or Z or any combination thereof.

While the above description describes features of example embodiments, it will be appreciated that some features and/or functions of the described embodiments are susceptible to modification without departing from the spirit and principles of operation of the described embodiments. For example, the various characteristics which are described by means of the represented embodiments or examples may be selectively combined with each other. Accordingly, what has been described above is intended to be illustrative of the claimed concept and non-limiting. It will be understood by persons skilled in the art that other variants and modifications may be made without departing from the scope of the invention as defined in the claims appended hereto. The scope of the claims should not be limited by the preferred embodiments and examples, but should be given the broadest interpretation consistent with the description as a whole.